The trouble with Mrs Kohl

Hannelore Kohl, wife of Germany's disgraced former chancellor, spent the last years of her life hiding from the sun. During the day, she sat in darkened rooms, shutters closed, curtains drawn. If she went out for a walk, she went in the evenings. In the final few months her condition deteriorated, and she rarely went out at all, shying away even from artificial light and complaining of pain and difficulty walking.

"Because of the light allergy, I cannot for the moment attend any official functions," she said in April. She would have loved to live in the flat which she and her husband had bought in Berlin and which she had decorated and furnished, "but I don't go there because our house in Oggersheim is bigger and I have more room to move around."

She revealed that she had been suffering from the problem since 1993, when she was given penicillin, to which she was allergic. She consequently developed photodermatitis, an itchy, scaly, blistery, reddening of the skin, caused by an increase of the skin's normal sensitivity to the effects of sunlight or ultraviolet rays. Her doctor was at a loss to know what to do, she said. A year earlier, she had undergone a desensitising treatment, but it had only made things worse. "I have to avoid going out only when the sun is shining," she said. "I can do so from to time when it is cloudy. I have to avoid dazzling light. Even artificial light."

Last Friday, Kohl was found dead at her Oggersheim home. The statement issued later by her husband's private office, which revealed that she had committed suicide, ascribed her decision to the "hopelessness of her medical situation". In their statement, her husband's aides said she had consulted experts inside and outside Germany, but without discovering anyone who could treat her successfully.

All this does not quite stack up, however, and for the German people, who held Kohl in great affection, her illness and death have become something of a mystery. Several of the country's leading skin and allergy specialists have been questioned by the media: none seems to have treated Kohl, or even been asked to do so. "I would gladly have provided intensive testing," says Johannes Ring of the Munich Technical University's department of dermatology.

Nor have any of Germany's specialists been able, on the basis of Kohl's own account, to identify the precise ailment from which she suffered. At least one has speculated that her condition was so rare as to be previously unknown.

Experts say that her condition doesn't fit with any recognised, acquired disorder for a woman of her age. The key irregularity is that while hundreds of drugs, including several antibiotics, can cause severe sensitivity to sunlight, the list does not include penicillin. Another problem is that this sensitivity generally lasts only as long as the course of drugs; at longest a year, say. Her sensitivity to artificial light is also curious: that would apparently only be expected if her eyes were the problem, rather than her skin, or with a condition called chronic actinic dermatititis (which is not painful, and is treatable). It's extremely strange that no German doctor could help her: they are advanced in this field.

The German public was never impressed by persistent rumours that the real reason for the Kohls' long separations was his affair with his secretary, and this is probably one reason for the heightened interest in the details of Hannelore's life and death. British doctors agree that the facts available don't make much sense.

"I can't reconcile the facts to hand with a dermatological diagnosis," says Ravi Ratnavel, a consultant dermatologist at Stoke Mandeville hospital. While refusing to rule out the possibility that penicillin could somehow, mysteriously, have caused a long-term, painful intolerance to sunlight, he clearly finds it unlikely.

According to Dr Nick Lowe, a consultant dermatologist at the Cranley Clinic in London, the most common form of sun intolerance is "polymorphous light eruption", from which he himself suffers. He says that about 14% of the population of northern Europe will experience this condition, characterised by itching, red bumps and sometimes blisters about two or three days after a period of exposure that's out of the ordinary - typically at the start of the summer. For these people, sunscreens that protect you from UVA are particularly effective, he says, but periods of exposure will harden up the skin as the summer goes on. In unusually severe cases, dermatologists can help with desensitising treatments using UV lamps.

Other forms of sun intolerance are caused by a cluster of diseases, largely genetic, called porphyrias. Patients in this group include the so-called "children of the moon". They have a condition called xeroderma pigmentosum, an extremely rare genetic disease that destroys the DNA's ability to repair itself. Any exposure to sunlight causes severe burns and even cancerous tumours. It's a hideously restrictive condition: you can only go outside at night, or wearing a specially designed spacesuit. Then there are a range of other conditions where one of the symptoms is increased sensitivity to the sun, such as lupus. But of course none of these could have been the cause of Mrs Kohl's problems.

Lowe says that in really severe cases of photosensitivity, as Kohl was apparently suffering from - regardless of why or how - treatments with drugs that suppress the immune system and oral cortisones may help. But then again, the cortisones may result in severe depression. "It's very complex," he says.

Thousands of Germans were in mourning yesterday as Kohl was buried. It seems likely that the truth about her illness, and the real reasons for her depression and suicide, were laid to rest with her.